This invention relates to a rolling track for a rotary hopper of a loading installation for a shaft furnace. More particularly, this invention relates to a new and improved rolling track for a rotary hopper comprised of a series of rollers which are supported by a fixed reinforcement and on which travels the circular pedestal of the hopper. In addition, this pedestal is equipped with a toothed ring in order to be driven in a rotary movement about the vertical axis of the pedestal.
While not being limited thereto in its utility, the present invention is well suited for use as a stand-by hopper for a central loading installation of a shaft furnace, particularly a blast furnace. It is well known that granular charging or loading material for use in a shaft furnace will undesirably segregate according to their granulometry when disposed in a stand-by hopper. To minimize the impact of this segregation phenomenon, a recent proposal has been to rotate the hopper during its loading and, if appropriate, also during its emptying. The simplest solution involves mounting, on the circular reinforcement (e.g. pedestal) supporting the hopper, a series of track rollers, on which the hopper can rotate under the action of a drive pinion meshing with a toothed ring of the hopper pedestal. To avoid the need to make these supporting track rollers oversized because of the weight of the hopper (several hundred tons under full load), at least a minimum number of rollers, for example eight rollers, must be provided. Initially, it would seem logical to uniformly distribute these rollers over the entire periphery of the circular supporting reinforcement.
However, it has been found that, in this case, the hopper is not uniformly supported by all the rollers. In fact, often the hopper is supported by only three of the rollers. This non-uniform support can be caused by an asymmetry of the weight of the batch, wear or deformation of some of the rollers, deposits of dirt on the rolling surface of the hopper, incorrect vertical adjustment of the rollers, etc. Not only does this non-uniform support result in a lack of stability of the hopper, but also all the rollers have to be designed so that three of them are capable of supporting the entire load so as to avoid the risk of premature wear. Besides the additional costs incurred as a result of such oversizing (the rollers are necessarily relatively large and wide), this oversizing contradicts the experience gained in this field where it has been found that the supporting track rollers must be as thin as possible to ensure rolling without friction and to prevent the wheels from bearing on one point only (for example, because of a slight deformation of the supporting framework).